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Internet Research Task Force (IRTF) RJ Atkinson
Request for Comments: 6743 Consultant
Category: Experimental SN Bhatti
ISSN: 2070-1721 U. St Andrews
November 2012
ICMP Locator Update Message for
the Identifier-Locator Network Protocol for IPv6 (ILNPv6)
Abstract
This note specifies an experimental ICMPv6 message type used with the
Identifier-Locator Network Protocol (ILNP). The Identifier-Locator
Network Protocol (ILNP) is an experimental, evolutionary enhancement
to IP. This message is used to dynamically update Identifier/Locator
bindings for an existing ILNP session. This is a product of the IRTF
Routing Research Group.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for examination, experimental implementation, and
evaluation.
This document defines an Experimental Protocol for the Internet
community. This document is a product of the Internet Research Task
Force (IRTF). The IRTF publishes the results of Internet-related
research and development activities. These results might not be
suitable for deployment. This RFC represents the individual
opinion(s) of one or more members of the Routing Research Group of
the Internet Research Task Force (IRTF). Documents approved for
publication by the IRSG are not a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6743.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document.
This document may not be modified, and derivative works of it may not
be created, except to format it for publication as an RFC or to
translate it into languages other than English.
Table of Contents
1. Introduction ....................................................3
1.1. Document Roadmap ...........................................3
1.2. ICMPv6 Locator Update ......................................4
1.3. Terminology ................................................5
2. Syntax ..........................................................5
2.1. Example ICMPv6 Locator Update Message ......................7
3. Transport Protocol Effects ......................................8
4. Implementation Considerations ...................................8
5. Backwards Compatibility .........................................8
6. Security Considerations .........................................9
7. IANA Considerations .............................................9
8. References .....................................................10
8.1. Normative References ......................................10
8.2. Informative References ....................................10
9. Acknowledgements ...............................................11
1. Introduction
This document is part of the ILNP document set, which has had
extensive review within the IRTF Routing RG. ILNP is one of the
recommendations made by the RG Chairs. Separately, various refereed
research papers on ILNP have also been published during this decade.
So, the ideas contained herein have had much broader review than the
IRTF Routing RG. The views in this document were considered
controversial by the Routing RG, but the RG reached a consensus that
the document still should be published. The Routing RG has had
remarkably little consensus on anything, so virtually all Routing RG
outputs are considered controversial.
At present, the Internet research and development community are
exploring various approaches to evolving the Internet Architecture to
solve a variety of issues including, but not limited to, scalability
of inter-domain routing [RFC4984]. A wide range of other issues
(e.g., site multihoming, node multihoming, site/subnet mobility, node
mobility) are also active concerns at present. Several different
classes of evolution are being considered by the Internet research
and development community. One class is often called "Map and
Encapsulate", where traffic would be mapped and then tunnelled
through the inter-domain core of the Internet. Another class being
considered is sometimes known as "Identifier/Locator Split". This
document relates to a proposal that is in the latter class of
evolutionary approaches.
1.1. Document Roadmap
This document defines a new ICMPv6 Locator Update message used by an
ILNP node to inform its correspondent nodes of any changes to its set
of valid Locators.
The ILNP architecture can have more than one engineering
instantiation. For example, one can imagine a "clean-slate"
engineering design based on the ILNP architecture. In separate
documents, we describe two specific engineering instances of ILNP.
The term "ILNPv6" refers precisely to an instance of ILNP that is
based upon, and backwards compatible with, IPv6. The term "ILNPv4"
refers precisely to an instance of ILNP that is based upon, and
backwards compatible with, IPv4.
Many engineering aspects common to both ILNPv4 and ILNPv6 are
described in [RFC6741]. A full engineering specification for either
ILNPv6 or ILNPv4 is beyond the scope of this document.
Readers are referred to other related ILNP documents for details not
described here:
a) [RFC6740] is the main architectural description of ILNP, including
the concept of operations.
b) [RFC6741] describes engineering and implementation considerations
that are common to both ILNPv4 and ILNPv6.
c) [RFC6742] defines additional DNS resource records that support
ILNP.
d) [RFC6744] defines a new IPv6 Nonce Destination Option used by
ILNPv6 nodes (1) to indicate to ILNP correspondent nodes (by
inclusion within the initial packets of an ILNP session) that the
node is operating in the ILNP mode and (2) to prevent off-path
attacks against ILNP ICMP messages. This Nonce is used, for
example, with all ILNP ICMPv6 Locator Update messages that are
exchanged among ILNP correspondent nodes.
e) [RFC6745] defines a new ICMPv4 Locator Update message used by an
ILNP node to inform its correspondent nodes of any changes to its
set of valid Locators.
f) [RFC6746] defines a new IPv4 Nonce Option used by ILNPv4 nodes to
carry a security nonce to prevent off-path attacks against ILNP
ICMP messages and also defines a new IPv4 Identifier Option used
by ILNPv4 nodes.
g) [RFC6747] describes extensions to the Address Resolution Protocol
(ARP) for use with ILNPv4.
h) [RFC6748] describes optional engineering and deployment functions
for ILNP. These are not required for the operation or use of ILNP
and are provided as additional options.
1.2. ICMPv6 Locator Update
As described in [RFC6740] and [RFC6741], an ILNP for IPv6 (ILNPv6)
node might need to inform correspondent ILNPv6 nodes of changes to
the set of valid Locator values. The new ICMPv6 Locator Update
message described in this document enables an ILNP-capable node to
update its correspondents about the currently valid set of Locators
valid to use in reaching the node sending this message [RFC2460]
[RFC4443].
This new ICMPv6 message MUST ONLY be used for ILNPv6 sessions.
Authentication is always required, as described in the Security
Considerations section later in this note.
Some might consider any and all use of ICMP to be undesirable. In
that context, please note that while this specification uses ICMP, on
grounds that this is a control message, there is no architectural
difference between using ICMP and using some other framing (for
example, UDP).
1.3. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Syntax
The ICMPv6 message described in this section has ICMP Type 156 and is
used ONLY with a current ILNPv6 session. This message enables an
ILNPv6 node to inform ILNPv6 correspondent nodes of changes to the
active Locator set for the ILNPv6 node that originates this message.
This particular ICMPv6 message MUST ONLY be used with ILNPv6
sessions.
This particular ICMPv6 message MUST ONLY be used with ILNPv6
sessions. The Checksum field for this message is calculated
identically as for any other ICMPv6 message.
ICMPv6 Locator Update message
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num of Locs | Operation | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Locator [1] /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference [1] | Lifetime [1] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Locator [2] /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference [2] | Lifetime [2] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
| . |
| . |
ICMPv6 Locator Update fields:
Type 156
Code 0
Checksum The 16-bit one's complement of the one's
complement sum of the ICMP message, starting
with the ICMP Type. For computing the
checksum, the Checksum field is set to 0.
Num of Locs The number of 64-bit Locator values that are
advertised in this message. This field MUST
NOT be zero.
Locator[i], The 64-bit Locator values currently
i = 1..Num of Locs valid for the sending ILNPv6 node.
Preference[i], The preferability of each Locator[i],
i = 1..Num of Locs relative to other valid Locator[i] values.
The Preference numbers here are identical,
both in syntax and semantics, to the
Preference values for L64 records as
specified by [RFC6742].
Lifetime[i] The maximum number of seconds that this
i = 1..Num of Locs particular Locator may be considered valid.
Normally, this is identical to the DNS
lifetime of the corresponding L64 record, if
one exists.
Operation The value in this field indicates whether
this is a Locator Update Advertisement
(0x01) or a Locator Update Acknowledgement
(0x02).
RESERVED A field reserved for possible future use.
At present, the sender MUST initialise this
field to zero. Receivers should ignore this
field at present. The field might be used
for some protocol function in future.
The Operation field has value 1 (hexadecimal 0x01) for a Locator
Update Advertisement. The Operation field has value 2 (hexadecimal
0x02) for a Locator Update Acknowledgement. All other values of the
Operation field are reserved for future use by future revisions of
this specification.
A node whose set of valid Locators has changed MUST send Locator
Update Advertisement messages to each correspondent node for each
active unicast ILNP session. For unicast ILNP sessions, the receiver
of a valid Locator Update Advertisement (e.g., authentication checks
all passed; advertisement is received from a current correspondent
node) addressed to the receiver MUST send a Locator Update
Acknowledgement back to the sender of the Locator Update
Advertisement. The Acknowledgement message body is identical to the
received Advertisement message body, except for the Operation value.
All ILNPv6 ICMP Locator Update messages MUST contain a valid ILNPv6
Identifier option and MUST contain an ILNPv6 Nonce Option.
ILNPv6 ICMP Locator Update messages also MAY be protected using IP
Security for ILNP [RFC6741] [RFC4301]. Deployments in high-threat
environments SHOULD also protect ILNPv6 ICMP Locator Update messages
using IPsec. While IPsec Encapsulating Security Payload (ESP) can
protect a payload, no form of IPsec ESP is able to protect an IPv6
option that appears prior to the ESP header.
Note that even when IP Security for ILNP is in use, the ILNP Nonce
Option still MUST be present. This simplifies protocol processing,
and it also means that a receiver can perform the inexpensive check
of the Nonce value before performing any (potentially expensive)
cryptographic calculation.
2.1. Example ICMPv6 Locator Update Message
This example shows the ICMPv6 syntax for the case where 2 Locator
values are being indicated.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num of Locs | RESERVED | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Locator [1] /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference [1] | Lifetime [1] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Locator [2] /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference [2] | Lifetime [2] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3. Transport Protocol Effects
This message has no impact on any transport protocol.
The message may affect where packets for a given transport-layer
session are sent, but an ILNP design objective is to decouple
transport-layer protocols and transport-layer session information
from network-layer changes.
4. Implementation Considerations
Implementers may use any internal implementation they wish, provided
that the external appearance is the same as this implementation
approach.
To support ILNPv6, and to retain the incremental deployability and
backwards compatibility needed, the network layer needs a mode bit in
the Transport Control Block (or its equivalent) to track which IP
sessions are using the classic IPv6 mode and which IP sessions are
using the Identifier/Locator Split mode.
Further, when supporting ILNPv4, nodes will need to support an
Identifier Locator Communication Cache (ILCC) in the network layer as
described in [RFC6741].
A node sending an ICMP Locator Update message MUST include all
currently valid Locator values in that message. A node receiving a
valid ICMP Locator Update message MUST replace the previously current
set of Locator values for that correspondent node in its own ILCC
with the newly received set of Locator values.
Every implementation needs to support a large number of Locator
values being sent or received in a single ICMP Locator Update
message, because a multihomed node or multihomed site might have a
large number of upstream links to different service providers, each
with its own Locator value.
5. Backwards Compatibility
This ICMPv6 message uses the same checksum calculations as any other
ICMPv6 message.
When ILNPv6 is not in use, the receiving IPv6 mode MUST discard the
ICMP Locator Update packet without processing the packet. This is
standard behaviour for a non-ILNPv6 node when receiving an ICMPv6
message with an unknown header field value.
6. Security Considerations
Security considerations for the overall ILNP architecture are
described in [RFC6740]. Additional common security considerations
are described in [RFC6741]. This section describes security
considerations specific to ILNPv6 topics discussed in this document.
The ICMPv6 Locator Update message MUST ONLY be used for ILNPv6
sessions.
The ILNP Nonce Destination Option [RFC6744] MUST be present in
packets containing an ICMPv6 Locator Update message. Further, the
received Nonce Destination Option MUST contain the correct nonce
value for the packet to be accepted by the recipient and then passed
to the ICMPv6 protocol for processing. If either of these
requirements are not met, the received packet MUST be discarded as a
forgery, and a security event SHOULD be logged by the system
receiving the non-authentic packet.
ILNP sessions operating in higher risk environments SHOULD use IP
Security for ILNP [RFC6741] [RFC4301] *in addition* to the ILNPv6
Nonce Destination Option. Use of IP Security for ILNP to protect a
packet does NOT permit the packet to be sent without the Nonce
Destination Option.
Implementations need to support the case where a single ICMP Locator
Update message contains a large number of Locator and Preference
values and ought not develop a security fault (e.g., stack overflow)
due to a received message containing more Locator values than
expected.
If the ILNP Nonce value is predictable, then an off-path attacker
might be able to forge data or control packets. This risk also is
mitigated by the existing common practice of IP Source Address
filtering [RFC2827] [RFC3704].
7. IANA Considerations
Consistent with the procedures of [RFC4443], IANA has assigned the
value 156 to the ICMP Type listed in Section 2.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC3704] Baker, F. and P. Savola, "Ingress Filtering for
Multihomed Networks", BCP 84, RFC 3704, March 2004.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", RFC 4443, March
2006.
[RFC6740] Atkinson, R. and S. Bhatti, "Identifier-Locator Network
Protocol (ILNP) Architectural Description", RFC 6740,
November 2012.
[RFC6741] Atkinson, R. and S. Bhatti, "Identifier-Locator Network
Protocol (ILNP) Engineering and Implementation
Considerations", RFC 6741, November 2012.
[RFC6744] Atkinson, R. and S. Bhatti, "IPv6 Nonce Destination
Option for the Identifier-Locator Network Protocol for
IPv6 (ILNPv6)", RFC 6744, November 2012.
8.2. Informative References
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP
Source Address Spoofing", BCP 38, RFC 2827, May 2000.
[RFC4984] Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report
from the IAB Workshop on Routing and Addressing", RFC
4984, September 2007.
[RFC6742] Atkinson, R., Bhatti, S. and S. Rose, "DNS Resource
Records for the Identifier-Locator Network Protocol
(ILNP)", RFC 6742, November 2012.
[RFC6745] Atkinson, R. and S. Bhatti, "ICMP Locator Update Message
for the Identifier-Locator Network Protocol for IPv4
(ILNPv4)", RFC 6745, November 2012.
[RFC6746] Atkinson, R. and S.Bhatti, "IPv4 Options for the
Identifier Locator Network Protocol (ILNP)", RFC 6746,
November 2012.
[RFC6747] Atkinson, R. and S. Bhatti, "Address Resolution Protocol
(ARP) Extension for the Identifier-Locator Network
Protocol for IPv4 (ILNPv4)", RFC 6747, November 2012.
[RFC6748] Atkinson, R. and S. Bhatti, "Optional Advanced Deployment
Scenarios for the Identifier-Locator Network Protocol
(ILNP)", RFC 6748, November 2012.
9. Acknowledgements
Steve Blake, Stephane Bortzmeyer, Mohamed Boucadair, Noel Chiappa,
Wes George, Steve Hailes, Joel Halpern, Mark Handley, Volker Hilt,
Paul Jakma, Dae-Young Kim, Tony Li, Yakov Rehkter, Bruce Simpson,
Robin Whittle, and John Wroclawski (in alphabetical order) provided
review and feedback on earlier versions of this document. Steve
Blake provided an especially thorough review of an early version of
the entire ILNP document set, which was extremely helpful. We also
wish to thank the anonymous reviewers of the various ILNP papers for
their feedback.
Roy Arends provided expert guidance on technical and procedural
aspects of DNS issues.
Authors' Addresses
RJ Atkinson
Consultant
San Jose, CA 95125
USA
EMail: rja.lists@gmail.com
SN Bhatti
School of Computer Science
University of St Andrews
North Haugh, St Andrews
Fife KY16 9SX
Scotland, UK
EMail: saleem@cs.st-andrews.ac.uk

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